を以て【をもって】

The expression を以て (をもって) is a formal, written-style grammar point with several distinct usages. It appears frequently in official announcements, business correspondence, ceremonies, and formal writing. It attaches to nouns and conveys meanings such as "by means of," "with," or "as of."

Means or method – "by means of," "with"

Used to indicate the means, tool, or method by which something is accomplished. This is a more formal equivalent of で.

Deadline or point in time – "as of," "effective"

Used to indicate a specific point in time at which something ends, starts, or takes effect. This usage is extremely common in formal announcements about closings, deadlines, and terminations.

Reason or basis – "on the grounds of," "because of"

Less commonly, を以て can indicate a reason or basis for something, similar to the formal をもって meaning "on account of."

Notes

• を以て is highly formal and literary. In everyday speech, で or をもって(written in hiragana) would be more natural for the "means" usage, and をさいご最後に or で for the "as of" usage.

• The kanji form もって以て is sometimes written entirely in hiragana as をもって or をもちまして (the latter being even more polite, using the ます stem of もつ持つ-derived honorific form).

• The expression これをもって以て ("with this") is a set phrase common to formally conclude meetings, ceremonies, or events.